Patent Literature 1 describes a snubber circuit used in a power conversion system such as an alternating-current/direct-current power converter.
In Patent Literature 1, an AC/AC frequency converter connected to a primary side of a high-frequency transformer includes a three-phase rectifier, an inverter, and a snubber circuit. The three-phase rectifier has an input side connected to a three-phase commercial AC power supply and an output side connected to an input side of the inverter. The input side of the inverter is connected to the output side of the three-phase rectifier, and an output side of the inverter is connected to the primary side of the high-frequency transformer. The snubber circuit is connected between the three-phase rectifier and the inverter.
The snubber circuit described in Patent Literature 1 absorbs, as energy, a spike-like overvoltage caused due to leakage inductance of the high-frequency transformer and regenerates the energy absorbed. The snubber circuit is an RCD single direction snubber circuit of regenerative type including a resistor, a capacitor, a diode, and a semiconductor switch.
In the RCD single direction snubber circuit as described in Patent Literature 1, at least part of the energy absorbed is converted into heat and consumed by the resistor. Thus, as electric power to be converted by the power conversion system increases, loss in the snubber circuit increases.